According to the French patent 2 847 051, a method is known that allows a physical quantity representative of an interaction between a wave and an obstacle to be evaluated. The implementation of this method is very useful in applications such as non-destructive testing. However, it can only be applied in a simple fashion to the case of a single interface separating one medium from another. Indeed, this method cannot be generalized to interactions with objects comprising several media, in particular owing to the high number of reflections and transmissions generated by the incident ultrasound wave when crossing the interfaces.